Bolt Circle Calculator
Calculate coordinates for evenly spaced bolt holes on a circle. Export to CSV, SVG, and G-code for your projects.
Quick Presets
Results
| Hole | Angle (°) | X | Y | Hole Dia |
|---|
How It Works
The bolt circle calculator computes coordinates for evenly spaced holes on a circle using trigonometric functions.
Formulas
For evenly spaced holes across a full or partial circle:
Angle step = arcDegrees / number of holes
Coordinates (with R = D/2):
xi = X0 + R × cos(θi × π/180)
yi = Y0 + R × sin(θi × π/180)
where θi = startAngle + direction × (i-1) × angleStep
Examples & Templates
Common bolt circle patterns:
- 4-hole pattern: Often used in flanges and simple fixtures
- 5-hole pattern: Common in automotive wheel applications
- 6-hole pattern: Standard for many industrial applications
- 8-hole pattern: Used in high-load applications
FAQ
For an even number of holes, measure directly between opposite holes. For an odd number, measure from the center of one hole to a point halfway between the two opposite holes.
The chord is the straight line distance between two points on a circle, while the diameter is the longest chord that passes through the center of the circle.
Common patterns include 4×100, 5×100, 5×114.3, 6×139.7, where the first number is the number of holes and the second is the bolt circle diameter in millimeters.